Water-based ink for ink jetting and ink jet recording method

ABSTRACT

A water-based ink for ink jetting and ink jet recording method, in which stable jetting, clearness of the recorded matter, high density recording, water resistance, and friction resistance are well-balanced, and being useful for ink for various types of ink jet recording. After 5% of the water soluble colored resin comprising 5,5′-dimethylhydantoinformaldehyde resin and color index number basic red 1:1 and 10% of polyethyleneglycol (average molecular weight 200) and 6% of triethyleneglycolmonometylether and 79% of pure water are fully stirred to be mixed, the mixture is filtered with a membrane filter of 0.8 μm thickness to become ink. Experimental evaluation using the recording head regarding jetting stability, jetting response, quality of the recorded images, friction resistance against various recording materials, and water resistance against various recording materials is made, and good results are obtained.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S. patentapplication Ser. No. 09/392,729, filed Sep. 9, 1999, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] The present invention is related to a water-based ink for inkjetting comprising water, a water soluble organic solvent and a coloringagent as essential components. The present invention is also related toan ink jet recording method for recording by flying minute droplets ofthe ink.

[0004] 2. Description of Related Art

[0005] In the ink jet recording method, ink droplets are formed byvarious ink jetting methods including the electrostatic suction method,a method of applying mechanical vibration or displacement using apiezoelectric element, or a method of generating bubbles by heating inkand utilizing pressure generated thereby, and recording is operated byadhering a part of or all of the formed droplets to a recording materialsuch as paper. A lot of development of the water-based ink using wateras a main solvent has been made for ink for the ink jet recordingmethod.

[0006] The water-based ink for ink jetting needs to meet some conditionsof no clogging at the head end portion of the recording apparatus or theink passage, stable jetting, providing recording images of clear tone ofcolor and sufficient high density and good water resistance and goodfriction resistance of the recorded matter.

[0007] Dye or pigment is generally used for a coloring agent of thewater-based ink for ink jetting.

[0008] Pigment is better than dye in terms of water resistance; however,pigment is worse in terms of the liquid stability and the dispersion ofthe pigment becomes unstable by the long period preservation or thewater evaporation because pigment is not dissolved but is dispersed inthe ink medium. Therefore, compared to the dye ink, the pigment ink iseasy to cause clogging at the end portion of the head of the ink jetprinter or in the ink passage. Because the pigment exists as a particleon the recorded matter, it has a problem in terms of the frictionresistance. Therefore, it is a rare case that the pigment ink for theink jet printer has become a commercial product, and most of the pigmentink is in the development stage.

[0009] Although the water soluble dye is worse in terms of the waterresistance compared to the pigment, the dye ink is hardly clogged at theend portion of the head of the ink jet printer or the ink passage and itis possible to acquire relatively easily a recorded matter of clearcolor tone and high density because the water soluble dye is completelydissolved in the ink medium. Therefore, there are many cases that thewater-based ink for ink jet printer using water soluble dye as acoloring agent has become a commercial product.

[0010] However, there has been no example of water-based ink for inkjetting that meets all conditions of sufficient jetting stability of inkjet recording, and clearness, high density recording, water resistanceand friction resistance of the recorded matter.

SUMMARY OF THE INVENTION

[0011] The present invention is to solve the above-described problems,and it is an object of the invention to provide a water-based ink forink jetting and ink jet recording method that meets all conditions ofsufficient jetting stability of ink jet recording, and clearness, highdensity recording, water resistance and friction resistance of therecorded matter.

[0012] In order to achieve the above-described object, water-based inkfor ink jetting of the present invention includes water soluble coloredresin wherein water soluble resin as a main component of the coloringagent is uniformly coloring processed by a basic dye.

[0013] According to the water-based ink for ink jetting of an embodimentof the present invention, the water soluble resin component of the watersoluble colored resin can be selected from5,5′-dimethylhydantoinformaldehyde resin obtained by copolymerization of5,5′-dimethylhydantoin and formaldehyde, or1-methylol-5,5′-dimethylhydantoin resin obtained by condensationpolymerization of 1-methylol-5,5′-dimethylhydantoin, orpolyvinylpyrrolidone obtained by addition polymerization ofvinylpyrolidone.

[0014] According to the water-based ink for ink jetting of an embodimentof the present invention, molecular weight of the water soluble resin ofthe water soluble colored resin can be equal to or less than 10000.

[0015] According to the water-based ink for ink jetting of an embodimentof the present invention, a compounding ratio of the water soluble resinand the basic dye in the water soluble colored resin can be within arange of 10:1 to 1:1.

[0016] According to the water-based ink for ink jetting of an embodimentof the present invention, a content amount of the water soluble coloredresin in the ink can be from 1 to 10 weight %.

[0017] According to the ink jet recording method of an embodiment of thepresent invention, a recording operation can be made by using thewater-based ink for ink jetting of the present invention.

[0018] As apparent from the above explanation, the water-based ink forink jetting of the invention includes water soluble colored resinwherein the water soluble resin as a main component of the coloringagent is uniformly coloring processed by the basic dye. Preferably, thewater soluble resin component of the water soluble colored resin isselected from 5,5′-dimethylhydantoinformaldehyde resin obtained bycopolymerization of 5,5′-dimethylhydantoin and formaldehyde, or1-methylol-5,5′-dimethylhydantoin resin obtained by condensationpolymerization of 1-methylol-5,5′-dimethylhydantoin, orpolyvinylpyrrolidone obtained by addition polymerization ofvinylpyrolidone. More preferably, molecular weight of the water solubleresin of the water soluble colored resin is equal to or less than 10000.More preferably, the compounding ratio of the water soluble resin andthe basic dye in the water soluble colored resin is within a range of10:1 to 1:1. More preferably, the content amount of the water solublecolored resin in ink is from 1 to 10 weight %. Therefore, the stablejetting, clearness of the recorded matter, high density recording, waterresistance, and friction resistance are well-balanced and excellent inink jet recording. The ink of the invention is useful for ink forvarious types of ink jet recording and the ink jet recording method usedwith the ink can provide excellent recording.

[0019] The ink jet recording method of the invention is characterized inrecording using the above-described water-based ink for ink jetting.Therefore, the stable jetting, clearness of the recorded matter, highdensity recording, water resistance, friction resistance arewell-balanced and excellent in ink jet recording. The ink of theinvention is useful for ink for various types of ink jet recording andthe ink jet recording method used with the ink can provide excellentrecording.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] The preferred embodiments of the invention will be explained.

[0021] Water soluble colored resin that is a main component of acoloring agent of the invention is water soluble resin that is uniformlycolored by basic dye. By using the water soluble colored resin as acoloring agent for the water-based ink for ink jetting, great excellentwater resistance can be obtained as compared to the water-based inkusing dye as a coloring agent. Because the water soluble colored resinis completely dissolved in the ink as same as the case that dye is usedas a coloring agent, recording excellent in clearness, high densityrecording and friction resistance can be obtained without obstructingthe stable jetting.

[0022] As used herein, the phrase “uniformly coloring processed by abasic dye” or similar phrases generally refers to a product obtained bytreating a water soluble resin with a basic dye, under specifiedconditions, whereby the basic dye and water soluble resin are bonded ata fixed ratio. The product, which can be described as a coloring agent,is in a form of microsuspension bodies (or, when suspended in anappropriate liquid medium such as water, colloidal particles) thatinclude both resin and dye molecules. Such a product is very differentfrom a product that results from the simple mixing of resin material anddye, as is conventionally used. Rather, the uniform color processingresults in a combination state maintained as a micro association body,where there exists a weak combination of the water soluble resin and thebasic dye, but where the basic dye is not chemically bonded to the watersoluble resin. In this form, the water soluble resin wraps or envelopsthe basic dye molecules to form weak bonds, such as by charge attractionforce, intramolecular force, and bonds between cubic molecules.

[0023] As described below, such micro association bodies are generallyformed by mixing the water soluble resin and basic dye under conditionswhere there is a high probability that the materials contact each other,and where the molecules can move freely. For example, this mixing can beprovided by the present invention by heating the materials to a suitabletemperature of, for example, a temperature of equal to or greater than60° C. This process is believed to provide the improved waterresistance, because the association between the resin molecules and dyemolecules is maintained even after mixing and printing is conducted.

[0024] The reason that the excellent water resistance can be obtained byusing the water soluble colored resin is as follows.

[0025] In the coloring process of the water soluble colored resin of theinvention, a weak combination of the water soluble resin and basic dyeis formed, and the combination is maintained as a minute associationbody after the water soluble colored resin is dissolved and mixed in theink. Namely, the basic dye on the recorded matter is maintained by thecombination with the water soluble resin and, therefore, even if wateris supplied after the recorded matter is dried, the basic dye is noteasily washed out by water by reason that the dispersion speed of thewater soluble resin into the water is slow.

[0026] Thus, by using water soluble colored resin, the water-based inkfor ink jetting and the ink jet recording method being excellent instable jetting, clearness, high density recording, water resistance andfriction resistance can be achieved.

[0027] The water soluble colored resin having solubility to water of 5%or more than 5% and slow dissolution speed and a characteristic that itsaqueous solution does not cause remarkable viscosity is preferably usedfor the invention. In particular, 5,5′-dimethylhydantoinformaldehyderesin obtained by copolymerization of 5,5′-dimethylhydantoin andformaldehyde, or 1-methylol-5,5′-dimethylhydantoin resin obtained bycondensation polymerization of 1-methylol-5,5′-dimethylhydantoin, orpolyvinylpyrrolidone obtained by addition polymerization, or derivativesthereof can be used for the water soluble colored resin of theinvention. However, the water soluble colored resin is not limited tothe above-described ones so long as the effect of the invention can beobtained. Moreover, more than two kinds of resins can be mixed to beused. The molecular weight of the water soluble resin is preferableequal to or less than 10000. As used herein, “mean (average) molecularweight” or “molecular weight” means weight average molecular weight.

[0028] Various ones on the market can be used for the basic dye of theinvention. In particular, color index number basic red 1, 1:1, 2, 12,13, 14, 18, 22, 27, 28, 29, 34, 38, 39, 46, 46:1, 67, 69, 70, colorindex number basic violet 1, 2, 3, 4, 5, 7, 8, 10, 11, 11:1, 20, 33,color index number basic blue 3, 6, 7, 9, 11, 12, 16, 17, 24, 26, 41,47, 66, color index number basic green 1, 4, 5, color index number basicyellow 1, 11, 19, 21, 24, 25, 28, 29, 36, 45, 51, 67, 73, color indexnumber basic orange 14, 21, 22, 32, color index number basic brown 1, 4can be used for the basic dye of the invention, however, the basic dyeis not limited to the above-described ones. Moreover, more than twokinds of basic dyes can be mixed to be used, and in this case, a desiredcolor that cannot be obtained by only one kind can be obtained.

[0029] Because the basic dye that is in the condition on the market mayinclude a great amount of inorganic impurities such as sodium sulfate, apurifying process by ion exchange resin or filtration can be provided ifnecessary. When the basic dye includes a great amount of inorganicimpurities, the combination in the coloring process may be obstructed orsufficient coloring may not be obtained or the inorganic impurities maybe deposited at the head end portion and cause clogging. From theabove-described points, the purity of the basic dye is preferably equalto or more than 90% and more preferably equal to or more than 95%.

[0030] The compounding ratio of the water soluble resin and the basicdye in the water soluble colored resin is preferably in the range from10:1 to 1:1. If the compounding ratio of the basic dye is less than theabove-mentioned ratio, sufficient coloring may not be obtained, and ifthe compounding ratio is more than the above-mentioned ratio, the effectof the combination of the water soluble resin and the basic dye may notbe fully obtained.

[0031] The water soluble colored resin of the invention can beprocessed, for example, by any one of the methods described below.

[0032] 1) Heating the water soluble resin to a temperature of equal toor more than 60° C. to make liquid of low viscosity, and adding thebasic dye to the liquid, and after mixing and stirring them to become anuniform condition, cooling it to the ordinary (i.e., room) temperatureto obtain the water soluble colored resin.

[0033] 2) Heating the nonvolatile organic solvent that is an inkcomponent to a temperature of equal to or more than 60° C., and afteradding the water soluble resin and basic dye to the heated solvent andmixing and stirring to become a uniform condition, cooling it to theordinary temperature to obtain the nonvolatile organic solvent solutionof the water soluble colored resin.

[0034] The preferable content by amount of the water soluble coloredresin obtained by the above-described method as a coloring agent inwater-based ink for ink jetting is 1-10 weight % relative to the totalamount of ink, more preferably 2-6 weight %. If the content by amount ofthe water soluble colored resin is less than 1 weight %, sufficientcoloring may not be obtained and the clear and high density recordingmay not be obtained. If the content by amount of the water solublecolored resin is more than 10 weight %, the ink may be more viscous thanis desirable, the stable jetting may be obstructed and drying of the inkon the recording paper may become extremely slow.

[0035] The solvent used in the invention can be a mixed solvent of waterand a water soluble organic solvent.

[0036] For water, general water containing various ions is notpreferable, but instead deionized water is preferable. The content byamount of water is decided in a broad range according to thecharacteristic of the desired ink, and generally the content by amountof water is 10-90 weight % relative to the total amount of ink,preferably 40-80 weight %.

[0037] The water soluble organic solvent is used mainly for the purposeof preventing drying of ink at the top end of the ink jet head,therefore, a solvent of low volatility is preferably used. Such watersoluble organic solvents include polyalkyleneglycol such aspolyethyleneglycol; alkyleneglycol such as ethyleneglycol,propyleneglycol, butyleneglycol, diethyleneglycol, depro pyleneglycol,triethyleneglycol, tripropyleneglycol, 1,2,6-hexanetriol, thiodiglycol,1,3-butanediol, 1,5-pentanediol, hexyleneglycol; and pyrolidone such as2-pyrolidone, N-methyl-2-pyrolidone. Either one kind of theabove-described water soluble organic solvents can be used, or more thantwo kinds of the above-described water soluble organic solvents can bemixed to be used.

[0038] The content amount of the above-described water soluble organicsolvent in the ink can be 5-50 weight % relative to the total amount ofink, preferably 7-40 weight %, more preferably 10-30 weight %. If thecontent amount of the water soluble organic solvent is less than 5weight %, the wetting operation may become insufficient and clogging maybe caused. If the content amount of the water soluble organic solvent ismore than 50 weight %, ink may be more viscous than is desirable, andjetting may become impossible and drying of the ink on the recordingpaper may become extremely slow.

[0039] The basic composition of the ink of the invention and used forthe invention is described above, and the various known agents such aspenetrating agent, dispersing agent, surface active agent, viscosityadjusting agent, surface tension adjusting agent, pH adjusting agent,antiseptics and mildewproof agent can be added if necessary.

[0040] As the penetrating agent, polyhydric alcohol monoalkylether thathas 0.1 mmHg or less than 0.1 mmHg of steam pressure at 20° C. ispreferably used. Polyhydric alcohol monoalkylether that hascharacterisitics as follows is preferably used; by gathering effectivelythe penetrating speed of ink into the recording paper, improving thefast drying of ink on the paper, preventing bleeding (bleeding on theborder of different colors) caused by the slow drying of ink on thepaper, and being difficult to cause feathering (feathering of a mustacheshape along the paper fiber).

[0041] Examples of polyhydric alcohol monoalkylether arediethyleneglycolmonomethylether (0.1 mmHg of steam pressure at 20° C.),diethyleneglycolmonobuthylether (0.01 mmHg of steam pressure at 20° C.),diethyleneglycolmonoisobuthylether (0.01 mmHg of steam pressure at 20°C.), dipropyleneglycolmonomethylether (0.06 mmHg of steam pressure at20° C.), dipropyleneglycolmonopropylether (0.02 mmHg of steam pressureat 20° C.), dipropyleneglycolmonoisopropylether (0.05 mmHg of steampressure at 20° C.), dipropyleneglycolmonobuthylether (0.05 mmHg ofsteam pressure at 20° C.), triethyleneglycolmonomethylether (less than0.01 mmHg of steam pressure at 20° C.), triethyleneglycolmonobuthylether(less than 0.01 mmHg of steam pressure at 20° C.),tripropyleneglycolmonomethylether (0.02 mmHg of steam pressure at 20°C.), and tripropyleneglycolmonobuthylether (less than 0.01 mmhg of steampressure at 20° C.).

[0042] General polyhydric alcohol monoalkylether has a peculiar smelland, if a polyhydric alcohol monoalkylether that has a steam pressure ofmore than 0.1 mmHg at 20° C. is used for ink, the ink itself may have aterrible smell and therefore it may cause a problem for use in theoffice or at home. However, the above-described polyhydric alcoholmonoalkylether that has a low steam pressure of 0.1 mmHg or less than0.1 mmHg at 20° C. has little smell if used for ink, and therefore theproblem described above does not result.

[0043] Moreover, among the above-described polyhydric alcoholmonoalkylether, those having less than 0.01 mmHg of steam pressure at20° C. have especially little smell and therefore they are preferablyused for ink. The content amount of the above-described polyhydricalcohol monoalkylether in the ink is preferably 3-15 weight % relativeto the total amount of ink. If the content amount of the above-describedpolyhydric alcohol monoalkylether is less than 3 weight %, thepenetrating speed of ink into the recording paper may be slow andproblems may be caused for drying time and bleeding. If the contentamount of the above-described polyhydric alcohol monoalkylether is morethan 15 weight %, ink may penetrate into the recording paper terriblyand ink may penetrate to the rear side of the recording paper and aproblem of feathering may be caused.

[0044] Monatomic alcohol such as ethylalcohol, 1-propanol, and2-propanol can be added if necessary for the purpose of controlling thedegree of penetration and drying.

[0045] When ink for the ink jet recording method of charging recordingliquid is compounded, a resistivity adjusting agent such as inorganicsalt including lithium chloride, ammonium chloride, or sodium chloridecan be added.

[0046] When the ink is used for the ink jet method of jetting ink by theoperation of heat energy, the material value of heat (for example,specific heat, coefficient of thermal expansion, and coefficient ofthermal conductivity) may be adjusted.

[0047] In the ink of the invention and the ink jet recording method usedwith the ink, the problems of the prior art are fully solved and thestable jetting, clearness of the recorded matter, high densityrecording, water resistance, and friction resistance are well-balancedand excellent ink jet recording is obtained. The ink of the invention isuseful for ink for various types of ink jet recording and the ink jetrecording method used with the ink can provide excellent recording.

[0048] Furthermore, the coloring agent of the present invention, beinguniformly coloring processed by a basic dye, provides inks and printedimages that exhibit improved color brightness and improvedwaterfastness. This is provided because the individual dye molecules arewrapped or enveloped by the water soluble resin separately, andmaintained in a micro association form.

[0049] The colorant of the claimed invention where the water solubleresin is uniformly coloring processed by a basic dye is thus differentfrom a mere mixture of a water soluble resin and basic dye. A meremixture of the specified components according to conventional processingdoes not result in a resin that is uniformly coloring processed by abasic dye, as specified in the present invention. In particular, theuniform color processing results in a colorant that exhibitssignificantly improved water resistance and provides improved colorbrightness compared to such conventional inks formed by mere mixing of awater soluble resin and basic dye.

[0050] Although not limited to any particular theory, it is believedthat the improved properties of the ink compositions of the presentinvention, including the improved color brightness and improvedwaterfastness, are achieved by the uniformly coloring process describedherein. Such process results is a more intimate mixture andinterrelation of the resin and dye molecules, providing an improved inkcomposition.

[0051] It is generally known in the art that a coloring efficiency of adye is dependent upon the excited state electron configuration of thedye molecules when exposed to light, and how stably that excited statecan be maintained. If a highly excited state can be provided and stablymaintained, i.e., if the excited state can be obtained and undesiredelectron exchange with other molecules does not occur, then a high colorbrightness can be reliably provided. This high and stable excitedelectron state is provided by the processes of the present invention.

[0052] In particular, mixed colloidal particles of the present inventionare formed by uniformly coloring processing a resin with a basic dye. Inthis form, the colloidal particles include both resin and dye moleculesin an intimate relationship, rather than only resin molecules or onlydye molecules. As a result of this intimate relationship, due moleculesare resin molecules are mixed with each other such that dye molecules donot necessarily contact only other dye molecules. Because dye moleculesdo not make contact only with each other, electron exchange between dyemolecules does not occur when the due molecules are in the excitedstate, and thus the excited state can be maintained independently of theadjacent dye molecules to provide a high coloring quality. In contrast,according to prior art ink compositions where dye molecules contact eachother in dye colloidal particles, electron exchange is easily performedbetween the adjacent dye molecules. Therefore, the excited state of thedye molecules is unstable and coloring quality is inferior. Theuniformly coloring process of the present invention thus provides an inkcomposition with improved coloring qualities.

[0053] Furthermore, the structure of the colloidal particles of the inkcompositions of the present invention are different than are provided byconventional ink compositions. This difference results in significantlyimproved waterfastness of the ink on a printed substrate.

[0054] Basic dyes, in contrast to other types of dyes such as acid dyesor direct dyes, generally have a low water solubility. The low watersolubility generally arises because the dye molecules have few oxygenatoms and/or because oxygen atoms that may be present in the moleculeare situated such that it is difficult for water to interact with theoxygen atom to solubilize the molecule. Accordingly, when the basic dyeis dissolved in water, the molecules tend to congregate and formcolloidal particles (referred to as “dye colloidal particles”).Dispersion of a water soluble resins in water also generally results ina similar composition. That is, when a water soluble resin is dissolvedin water, resin particles also tend to congregate and form colloidalparticles (refer to as “resin colloidal particles”), generally becausethe resin particles are an organic substance.

[0055] However, in such conventional ink compositions, the water solubleresin does not combine with the dye colloidal particles when forming themixture in water, and instead resin colloidal particles are formed asseparate entities from the dye colloidal particles. Even if the watersoluble resin is added to the solution of dye colloidal particles, theresult is to form separate resin colloidal particles along with the dyecolloidal particles, so that two separate kinds of colloidal particlesexist in solution. This result is that the dye colloidal particles andresin colloidal particles are separately dispersed in the water. Whenprinting is conducted using the conventional ink compositions, theresult is that the resin colloidal particles of the ink are stronglyfixed to the substrate (e.g., paper) because they are resins; however,the dye colloidal particles are generally poorly fixed to the substrate,since they are not intimately related to the resin colloidal particles.Accordingly, water resistance of the ink composition on the substrate islow, since water can more easily liberate the dye colloidal particlesfrom the substrate, leaving behind the resin colloidal particles.

[0056] The present invention, however, overcomes the above problems byuniformly coloring processing a resin with a basic dye. In the inks ofthe present invention, the dye particles and resin particles areintimately mixed and associated with one another, rather than beingseparated in separate colloidal particles as described above forconventional inks. In the present invention, the dye molecules areintimately mixed and associated with the rein particles. That is, thewater soluble resin is uniformly colorant processed by the basic dye.Once this composition is formed, the resin/dye combination can bedissolved in water to form a mixture, where mixed colloidal particlesare formed that include water soluble resin uniformly colorant processedby a basic dye. When printing is conducted using the ink compositionprepared according to the present invention, where mixed colloidalparticles exist in solution, improved fixing of both the dye and theresin to the substrate is achieved. Because the mixed colloidalparticles include both dye and resin, the colloidal particles are firmlyfixed to the substrate by the resin component. However, because the dyeis intimately mixed and associated with the resin, improved waterresistance is achieved since the dye cannot be as easily liberated fromthe fixed resin by the presence of water.

EXAMPLES

[0057] Examples of the invention will be explained.

[0058] In the following discussion and the tables, % means percent byweight.

[0059] The water soluble colored resin of the invention is obtained asdescribed in table 1. TABLE 1 Sample 1 Sample 2 Sample 3 Sample 4 Sample5 Sample 6 Sample 7 DMH  80%  90%  75%  60% MDMH  60%  80% PVP  10%BR1:1  20% BB3  10% BY40  25%  20% BV1  20% BV11:1  40%  20%  10% PEG 80% total 100% 100% 100% 100% 100% 100% 100%

[0060] In Samples 1-6 of coloring resin, the water soluble resindescribed in each Sample is melted to become liquid under a condition ofthe heating temperature of approximately 120° C. and the basic dyedescribed in each Example is added thereto and mixed and stirred for onehour and after that the mixture is cooled to become a normal temperatureand the solid material of coloring resin is obtained.

[0061] In Sample 7 of coloring resin, the water soluble resin describedin the Sample and the basic dye described in the Sample are added to thewater soluble organic solvent described in the Sample that is heated to100° C. and stirred to be mixed for two hours and after that the mixtureis cooled to become a normal temperature and the water soluble organicsolvent of the coloring resin is obtained.

[0062] The molecular weight of the water soluble resin described inTable 1 is an average molecular weight, and it can be obtained by thelight scattering method or the gel filtration chromatography.

Example 1

[0063] liquid composition coloring resin Sample 1  5% polyethyleneglycol(average molecular weight 200) 10% triethyleneglycolmonomethylether  6%pure (deionized) water 79%

[0064] After the above described materials are stirred to be mixed forenough time, the mixture is filtered with a membrane filter of 0.8 μmthickness to become ink.

[0065] By using the above-obtained ink in the following recordingapparatus, the following experimental evaluation is made and goodresults are obtained in the recording apparatus. The recordingapparatuses include: a recording apparatus having an on-demand typemulti head (a diameter of jetting orifice is 35 μm, a value of a heatingresistor is 150 Ω, driving voltage is 30V, frequency is 2 KHz) thatgenerates ink droplets by applying heat energy to the ink in therecording head.

[0066] (Experimental evaluation 1) jetting stability: In each of theatmosphere of the room temperature (25° C.), 5° C., and 40° C.,successive jetting is made for 24 hours. Stable and high qualityrecording is made from the beginning to the end.

[0067] (Experimental evaluation 2) jetting response: It is evaluated forthe intermittent jetting of every two seconds and jetting aftertwo-months of non-use, no clogging is caused at the top end of theorifice in either case and stable and uniform recording is made.

[0068] (Experimental evaluation 3) quality of recorded images: An imagerecorded on the following recording materials has high density andclearness and its color tone is clear magenta.

[0069] Recording Materials:

[0070] “XEROX 4200” of XEROX

[0071] “XEROX L” of XEROX

[0072] “HAMMERMIL COPYPLUS WHITE” of non size paper

[0073] “TOYO FILTER PAPER No.4” non size paper of TOYO ROSHI

[0074] (Experimental evaluation 4) friction resistance of each recordingmaterial: After five minutes the jetting recording is made onto therecording materials described in Experimental evaluation 3, it ischecked whether any image shear or blur is caused by rubbing the inkadhering part by a finger. There is no image shear or blur and therecorded image has excellent fixing.

[0075] (Experimental evaluation 5) water resistance of each recordingmaterial: After the recording materials having the characters and imagesrecorded thereon described in Experimental evaluation 3 are soaked intap water for thirty seconds and are taken out of the tap water anddried naturally, the degradation of the recorded characters and imagesis checked. There is no blur and the recorded characters can be read.

Example 2

[0076] Ink is prepared using the following liquid composition by thesame method as of Example 1 and the evaluation of Experimentalevaluation 1-5 is made using the recording apparatus as in Example 1.Excellent results are obtained as in Example 1. The color tone inExperimental evaluation 3 is clear magenta. liquid composition coloringresin Sample 2  5% polyethyleneglycol (average molecular weight 200) 10%triethyleneglycolmonomethylether  6% pure (deionized) water 79%

Example 3

[0077] Ink is prepared using the following liquid composition by thesame method as Example 1 and the evaluation of Experimental evaluation1-5 is made using the recording apparatus as in Example 1. Excellentresults are obtained as in Example 1. The color tone in Experimentalevaluation 3 is clear yellow. liquid composition coloring resin Sample 3 5% polyethyleneglycol (average molecular weight 200) 10%triethyleneglycolmonomethylether  6% pure (deionized) water 79%

Example 4

[0078] Ink is prepared using the following liquid composition by thesame method as Example 1 and the evaluation of Experimental evaluation1-5 is made using the recording apparatus as in Example 1. Excellentresults are obtained as in Example 1. The color tone in Experimentalevaluation 3 is clear black. liquid composition coloring resin Sample 4 5% polyethyleneglycol (average molecular weight 200) 10%triethyleneglycolmonomethylether  6% pure (deionized) water 79%

[0079] Next, the full color recording is made by the recording apparatusdescribed in Example 1 using the ink of Examples 1-4 as magenta ink,cyan ink, yellow ink and black ink respectively, and the recordingresult having clearness, high density and good color tone is obtained.The recorded images and characters do not have any bleeding orfeathering and they have good printing quality.

Example 5

[0080] Ink is prepared using the following liquid composition by thesame method as Example 1 and the evaluation of Experimental evaluation1-5 is made using the recording apparatus as in Example 1. Excellentresults are obtained as in Example 1. liquid composition coloring resinSample 5  2% glyceline 20% 2-pyrolidone 10%triethylenglycolmonobuthylether  4% pure (deionized) water 64%

Example 6

[0081] Ink is prepared using the following liquid composition by thesame method as Example 1 and the evaluation of Experimental evaluation1-5 is made using the recording apparatus as in Example 1. Excellentresults are obtained as in Example 1. liquid composition coloring resinSample 6  4% glyceline 25% triethylenglycolmonobuthylether  8% pure(deionized) water 63%

Example 7

[0082] Ink is prepared using the following liquid composition by thesame method as Example 1 and the evaluation of Experimental evaluation1-5 is made using the recording apparatus as in Example 1. Excellentresults are obtained as in Example 1. liquid composition coloring resinSample 7 20% (including 16% of polyethyleneglycol) color index numberbasic yellow 37  1% 2-pyrolidone 10% triethylenglycolmonobuthylether  4%pure (deionized) water 65%

Comparative Example 1

[0083] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 3, the recording lacks clearness and has low density. InExperimental evaluation 5, terrible blur is generated and the recordedcharacters are hard to read. liquid composition color index numberdirect red 227  1% polyethyleneglycol (average molecular 10% weight 200)triethyleneglycolmonomethylether  6% pure (deionized) water 83%

Comparative Example 2

[0084] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 3, the clearness of the images is not sufficient and inExperimental evaluation 5, although the recorded characters can be read,many blurs are caused. liquid composition color index number basicviolet 11:1  1% polyethylenecglycol (average molecular 10% weight 200)triethyleneglycolmonomethylether  6% pure (deionized) water 83%

Comparative Example 3

[0085] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 1, unstable jetting is observed partly. In Experimentalevaluation 2, bent jetting or non-jetting is caused in the jetting aftertwo-months of non-use. liquid composition coloring resin Sample 1 15%polyethyleneglycol (average molecular 10% weight 200)triethyleneglycolmonomethylether  6% pure (deionized) water 69%

[0086] Next, the comparative coloring resin is obtained for comparativeexamples as shown in Table 2. TABLE 2 Comparative coloring resin Sample1 Sample 2 Sample 3 DMH  30%  80% PVP(2)  24% BR1:1  70%  6% DR227  20%Water  70% Total 100% 100% 100%

[0087] In the comparative coloring resin Samples 1 and 2, the watersoluble resin described in each Comparative Sample is melted to becomeliquid under a condition of the heating temperature of approximately120° C. and the dye described in each Comparative Sample is addedthereto and mixed and stirred for one hour and after that the mixture iscooled to become a normal temperature and a solid material ofcomparative coloring resin is obtained.

[0088] In the comparative coloring resin Sample 3, the water solubleresin described in the example and the basic dye described in theexample are mixed in the solvent of water and stirred for one hour at anormal temperature. After that a solid material of the comparativecoloring resin is obtained by the freeze drying method.

Comparative Example 4

[0089] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 5, an apparent blur is caused. liquid composition comparativecoloring resin Sample 1  3% polyethyleneglycol (average molecular 10%weight 200) triethyleneglycolmonomethylether  6% pure (deionized) water81%

Comparative Example 5

[0090] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 3, the recording lacks clearness and has low density. InExperimental evaluation 5, terrible blur is caused and the recordedcharacters cannot be read. liquid composition comparative coloring resinSample 2  5% polyethyleneglycol (average molecular 10% weight 200)triethyleneglycolmonomethylether  6% pure (deionized) water 79%

Comparative Example 6

[0091] Ink is prepared using the following liquid composition by thesame method as Example 1 and Experimental evaluation 1-5 is made usingthe recording apparatus as in Example 1. As a result, in Experimentalevaluation 1, unstable jetting is observed frequently. In Experimentalevaluation 2, bent jetting or non-jetting is caused in the jetting aftertwo-months of non-use. liquid composition comparative coloring resinSample 3  4% triethyleneglycol 16% pure (deionized) water 80%

[0092] The results of Experimental Evaluation 1-5 for theabove-described Examples and Comparative Examples are described in Table3. TABLE 3 Experimental Evaluation 1 2 3 4 5 Example 1 ⊚ ⊚ ⊚ ⊚ ⊚ Example2 ⊚ ⊚ ⊚ ⊚ ⊚ Example 3 ⊚ ⊚ ⊚ ⊚ ⊚ Example 4 ⊚ ⊚ ⊚ ⊚ ⊚ Example 5 ⊚ ⊚ ⊚ ⊚ ⊚Example 6 ⊚ ⊚ ⊚ ⊚ ⊚ Example 7 ⊚ ⊚ ⊚ ⊚ ⊚ Comparative ◯ ◯ Δ ◯ X Example 1Comparative ◯ ◯ Δ ◯ Δ Example 2 Comparative Δ Δ ◯ ⊚ ⊚ Example 3Comparative ⊚ ⊚ ⊚ ⊚ Δ Example 4 Comparative ⊚ ⊚ Δ ◯ X Example 5Comparative X X ⊚ ⊚ ⊚ Example 6

[0093] As described in Table 3, in Examples of the invention, the stablejetting, clearness of the recorded matter, high density recording, waterresistance, and friction resistance are well-balanced and excellent inkjet recording is obtained. The ink of the invention is useful for inkfor various types of ink jet recording and the ink jet recording methodused with the ink can provide excellent recording. On the other hand, inthe Comparative Examples, a problem is caused in at least one of theExperimental Evaluations.

What is claimed is:
 1. Water-based ink for ink jetting comprising water,a water soluble organic solvent and a coloring agent as essentialcomponents, wherein the coloring agent comprises a water soluble coloredresin wherein a water soluble resin as a main component of the coloringagent is uniformly coloring processed by a basic dye.
 2. The water-basedink for ink jetting according to claim 1, wherein the water solubleresin component of the water soluble colored resin is selected from thegroup consisting of 5,5′-dimethylhydantoinformaldehyde resin obtained bycopolymerization of 5,5′-dimethylhydantoin and formaldehyde,1-methylol-5,5′-dimethylhydantoin resin obtained by condensationpolymerization of 1-methylol-5,5′-dimethylhydantoin, andpolyvinylpyrrolidone obtained by addition polymerization ofvinylpyrolidone.
 3. The water-based ink for ink jetting according toclaim 1, wherein a weight molecular weight of the water soluble resin ofthe water soluble colored resin is equal to or less than
 10000. 4. Thewater-based ink for ink jetting according to claim 1, wherein acompounding ratio of the water soluble resin and the basic dye in thewater soluble colored resin is within a range of 10:1 to 1:1.
 5. Thewater-based ink for ink jetting according to claim 1, wherein a contentamount of the water soluble colored resin in the ink is from 1 to 10weight %.
 6. The water-based ink for ink jetting according to claim 2,wherein the 5,5′-dimethylhydantoinformaldehyde resin is obtained bycopolymerization of 5,5′-dimethylhydantoin and formaldehyde, the1-methylol-5,5′-dimethylhydantoin resin is obtained by condensationpolymerization of 1-methylol-5,5′-dimethylhydantoin, and thepolyvinylpyrrolidone is obtained by addition polymerization ofvinylpyrolidone.
 7. The water-based ink for ink jetting according toclaim 1, wherein the coloring agent is in a form of microsuspensionbodies that include both resin and dye molecules.
 8. Ink jet recordingmethod for a recording operation by flying minute droplets ofwater-based ink for ink jetting that comprises water, a water solubleorganic resin and a coloring agent as essential components, wherein thewater-based ink for ink jetting of claim 1 is used as the ink. 9.Water-based ink for ink jetting comprising water, a water solubleorganic solvent and a coloring agent as essential components, whereinthe coloring agent comprises a water soluble colored resin formed byuniformly coloring processing a water soluble resin by a basic dye. 10.The water-based ink for ink jetting according to claim 9, wherein thewater soluble resin component of the water soluble colored resin isselected from the group consisting of 5,5′-dimethylhydantoinformaldehyderesin obtained by copolymerization of 5,5′-dimethylhydantoin andformaldehyde, 1-methylol-5,5′-dimethylhydantoin resin obtained bycondensation polymerization of 1-methylol-5,5′-dimethylhydantoin, andpolyvinylpyrrolidone obtained by addition polymerization ofvinylpyrolidone.
 11. The water-based ink for ink jetting according toclaim 9, wherein a weight molecular weight of the water soluble resin ofthe water soluble colored resin is equal to or less than
 10000. 12. Thewater-based ink for ink jetting according to claim 9, wherein acompounding ratio of the water soluble resin and the basic dye in thewater soluble colored resin is within a range of 10:1 to 1:1.
 13. Thewater-based ink for ink jetting according to claim 9, wherein a contentamount of the water soluble colored resin in the ink is from 1 to 10weight %.
 14. The water-based ink for ink jetting according to claim 10,wherein the 5,5′-dimethylhydantoinformaldehyde resin is obtained bycopolymerization of 5,5′-dimethylhydantoin and formaldehyde, the1-methylol-5,5′-dimethylhydantoin resin is obtained by condensationpolymerization of 1-methylol-5,5′-dimethylhydantoin, and thepolyvinylpyrrolidone is obtained by addition polymerization ofvinylpyrolidone.
 15. The water-based ink for ink jetting according toclaim 9, wherein the coloring agent is in a form of microsuspensionbodies that include both resin and dye molecules.
 16. The water-basedink for ink jetting according to claim 9, wherein the uniformly coloringprocessing is conducted at a temperature about 60° C. or higher.
 17. Inkjet recording method for a recording operation by flying minute dropletsof water-based ink for ink jetting that comprises water, a water solubleorganic resin and a coloring agent as essential components, wherein thewater-based ink for ink jetting of claim 9 is used as the ink.
 18. Aprocess for forming a water-based ink for ink jetting comprisinguniformly coloring processing a water soluble resin by a basic dye toform microsuspension bodies; dispersing said microsuspension bodies in aliquid medium comprising water and a water soluble organic solvent. 19.The process according to claim 18, wherein the uniformly coloringprocessing is conducted at a temperature about 60° C. or higher.